Bulk fruit containers are typically containers having a xe2x80x9cfootprintxe2x80x9d the size of a typical pallet which may be used to transport fruit and the like.
Bulk fruit containers may be disposable and made of cardboard or the like or partially or totally reusable. Partially or totally reusable bulk containers have a plastics base and side walls of cardboard or plastics material.
The use of cardboard for bulk containers is becoming less acceptable since the cardboard remains at the destination and is considered waste. The European Union is proposing to require all retail packaging material imported into the EU to be removed to the country of origin. This makes the use of reusable bulk containers much more attractive, if not essential, than previously.
Whilst reusable bulk containers exist, they suffer from lack of durability, rigidity and poor volumetric efficiency and excessive height when folded.
The present invention, in its various forms, aims to improve the performance of folding balk containers in these areas.
Some existing base units for bulk containers are injection moulded as a single structure, with the support feet integral with the base. To form the feet with a continuous surface, openings must be left in the upper surface of the base, which are then closed with press-in inserts. This construction may result in a weak base with insufficient rigidity of the base. The base tends to fail at the junction of the feet, particularly if the base is held in racks and only supported at its edges or corners.
A base unit may be made with separate feet and base which are subsequently welded together. These units are moved by fork lift when loading or unloading trucks or being otherwise moved. The feet are frequently hit either by the tyres of the fork lift or are hit against a solid object, such as the top of a loading dock or the side of a truck. This can shear off the feet at the weld line.
Accordingly in an attempt to improve the durability and rigidity of the base of a bulk container, one aspect of the invention provides a base unit including:
a base having an underside surface;
at least one support mounted to the underside of the cross-sectional base;
one of the support and base having at least one male extension extending into a female receptacle in the other of the support and the base, said male extension having a cross-sectional width in a transverse direction and a cross-sectional length in a longitudinal direction, said female receptacle having a cross-sectional width in the transverse direction and a cross-sectional length in the longitudinal direction, wherein the cross-sectional width of the male extension and female receptacle extension are substantially the same and the cross-sectional length of the female receptacle is greater than he cross-sectional length of the respective male extension.
Preferably the at least one support is friction welded to he base.
Preferably the male extension is circular in cross-section and the receptacle is an oval in cross-section. However, a square or rectangular extension may be used with a rectangular receptacle or any other appropriate shape.
The cross-sectional length of the receptacle needs to be sufficiently large to enable free movement of the male extension in the longitudinal direction during friction welding. This helps withstand lateral and longitudinal impacts.
Most containers have three feet spaced across the width of the base. These feet are usually of the same width. In preferred forms of the invention, the central foot should be increased to nearly double the width of the edge feet (whereas conventional art usually has substantially equal width). This invention creates a significantly reduced unsupported span, thereby increasing the rigidity of the base.
Existing folding bulk containers have four side walls which move between erect positions and collapsed positions. The base of the container has a peripheral wall running along each edge In existing containers the peripheral wall extends upwards more than 30 mm to 40 mm. The side walls, in the erect position, overlap the peripheral wall, so that any load on the side wall is transferred to the base of the container via the peripheral wall. Substantially most of the load is transferred Trough the hollow comers of the end wall. Most current systems have side walls which are about 40 mm thick and peripheral walls more than half tie thickness of the side wall. Further, many existing systems have a lift up/drop down type of pivoting arrangement rather than a true revolving action about a single, fixed axis. These factors tend to lead to excessive free play in the side walls and, more importantly excess collapsed height. In most systems the outer surface of the first side walls lies level with the upper edge of the peripheral wall. The side walls lock together in a way which requires one pair of opposed walls to have a female receptacle structure extending out of the general plane of the inner surface of the second side wall. This pair of walls is folded on top of the first pair and are mounted higher than the first pair so that this receptacle structure can lie on the horizontal outer surface of the first pair. This leads to excessive folded height
An aspect of the invention aims to reduce the height of a folded bulk container by providing a base unit having:
an elongate edge wall, said wall having an inner surface;
a side wall pivotably mounted on the base inwardly of the inner wall surface about a revolving axis substantially parallel to the edge wall;
said side wall being movable between an erect position in which it is approximately vertical and a folded position in which it is substantially approximately horizontal;
said side wall having a first portion having first outer surface which, when in the erect position, extends generally vertically adjacent to the inner wall surface to at least the highest point of the edge wall, and when in the folded position extends generally horizontally below a horizontally plane passing through the said highest point.
The side wall preferably has a second portion with a second outer surface and the edge wall has an outer surface which is coplanar with the second outer sure when the side wall is in the erect position.
Preferably the edge wall has a top surface which may be flat or radiused and extending between generally downwardly between the inner surface to the outer surface.
Preferably there is an intermediate surface on the side wall extending between the first and second outer surfaces and preferably this intermediate surface is complementary to the top surface of the edge wall.
In the preferred embodiment the peripheral edge walls only extend upwards by 28 mm while the side walls are 40 mm thick. The first portion of the side wall, which lies adjacent the edge wall, is only 28 mm thick so that when folded it lies flush with the upper surface of the edge wall with the major portion of the side wall above the edge wall. This step at the edge the side wall is of sufficient height to receive the female receptacle structure of the second pair of walls, so that the inner surface of the second pair of walls may lie upon the outer surface of the first pair of side walls. Compared to conventional folding containers this saves a significant amount in folded heightxe2x80x9412 mm in edge wall height and 12 mm in the mounting of the second pair of walls relative to the first pair.
As mentioned, existing folding bulk containers suffer from excessive free play in the side walls when erecting. In particular, the side walls may be pivoted more 90xc2x0. This can result in damage to the hinge or likewise the end wall. In an attempt to reduce or eliminate this free play the invention in another aspect provides a folding bulk container including:
a base unit including a peripheral edge wall which has an outer surface, an inner surface and an upper surface, and
a side wall pivotably mounted on the base unit about an axis adjacent the edge wall for movement between an erect position and a folded position.
The edge wall may have an outer surface, an inner surface and an upper surface which extends upwardly from the outer surface to the inner surface.
Preferably the upper surface is inclined or arched at about 12xc2x0 to the horizontal and the side wall has a surface complementary to the upper surface.
The geometry of the hinge pin relative to the bottom of the side and end walls is such that when the wall is moved through the arc from horizontal to vertical, the bottom of the walls lock against the floor of the base thereby discouraging the wall from going beyond 90 degrees. The unique nature of this geometry creates a secondary prevention of the wall being forced beyond 90 degrees in the form of the recessed lower bottom of the walls passing through an arc, the centre of which has placed the barrel hinge outer a full 40 mm inside the pallet base from the exterior of the peripheral wall and against the inner edge. This arc settles on top of the sloped peripheral wall, thereby locating the side wall in the upright position. The pin centre in the preferred forms of the invention is about 32 mm from the outer wall. Prior to this invention known art placed the pin within the peripheral wall.
Bulk containers are normally square or rectangular and pallet sizes vary with countries. In some countries the short side of a rectangular pallet does not allow the long side""s side walls to fold down without overlapping. This means the upper of the long side walls does not fold horizontally, which in turn means that the short side walls cannot fold down horizontally, so increasing the folded height of the container
Accordingly, in another aspect of the invention, there is provided a base unit for a collapsible bulk container in which side walls are pivotably mounted on the base unit, between erect and folded positions, said base unit having an upper surface against which all or part of the inner surface of at let one of the side walls rests when in the folded position, said upper surface and said inner surface configured to allow the said at least one side wall to pivot more than 90xc2x0 between thee vertical position and the folded position.
In a preferred embodiment this is achieved by having a V-shaped upper surface is Preferably the upper surface is symmetrical so that it does not matter which side wall is folded down first.
Preferably the lower of the two side walls pivots sufficiently to allow the second side wall to lie horizontally and lower than would otherwise be the case without this V.
In present folding bulk containers, the folding side walls engage with square or rectangular or circular shaped latches. Such configurations require undesirable looseness, since the lower latches travel through a smaller arc than the upper latches. In many systems the lower latches start to enter their respective female receptacle at about 45xc2x0 whilst the upper latches enter almost horizontally.
To achieve a rigid design while allowing the side walls to pivot about a fixed axis, the invention, in yet another broad form, provides a folding bulk container having:
a base;
side walls pivotably mounted on the edges of tie base for movement between folded position and erect positions;
adjacent pairs of erect side walls engaging each other by a series of engaging male tabs and female receptacles;
said male tabs extending from an end wall of a fist pair of side walls and engaging in said female receptacles in an inner wall of the other of said pair,
said tabs and receptacles extending away from tie axes of rotation of the two side walls;
said tabs and receptacles having a generally triangular shape, the included angle of the apex of the tab and corresponding receptacle being less than the included angle of the apex of the adjacent tab nearer to the axis.
Preferably, the included angle of the apex of each tab ranges from about 80xc2x0 adjacent the axis to about 20xc2x0 furthest from the axis.
The receptacles near to or adjacent the axis may have a short horizontal lead in.
The included angle of the apex is preferably inversely proportional to the distance of the apex from the axis.
All tabs preferably have the same dimension across the thickness of the respective side wall.
With corrugated cardboard walled containers, the volumetric efficiency is determined in part by the thickness of the peripheral edge walls. Typically these walls are about 24 mm or more wide and are formed as an upturned U with parallel side walls about 4 mm thick with a gap of about 16 mm. Using a blade between the side walls to form the gap requires a blade this thick to allow for proper cooling of the blade-thinner blades overheat. The present invention uses gas assist to create the actual peripheral wall, which may be reduced to an overall width of only 12 mm. Prior to this invention gas had been used to fill voids but never to create an entire wall. On a conventional pallet this can lead to a direct 4%-5% increase in internal volume.
Accordingly, in another aspect the invention provides an injection moulded plastics base including:
an upper surface;
an elongate peripheral wall extending from the upper surface along or adjacent at least part of the peripheral edge of the base, said peripheral wall being gas blown and extending along the length of the wall between inner and outer side walls.
The inner and outer walls are preferably each about one third the thickness of the peripheral wall
The stability of a stack of bulk containers may be improved if the stacks are positively locked together to act against creep or slip.
Accordingly, in yet a further aspect of the invention, there is provided a foldable bulk container including:
a base having longitudinally extending feet extending downwardly along or adjacent two spaced apart side edges;
side walls pivotably mounted on the base for movement between upright erect positions and horizontal folded positions, each of sad side walls having an inner surface, an outer surface, a thickness and an upper surface extending from the outer surface to said inner surface, wherein;
in said erect position said upper surface has a first portion which extends downwardly and inwardly from the outer surface and a second portion which extends inwardly and upwardly to said inner surface, and
each of said legs have a lower surface, including a portion which extends upwardly and inwardly complementary to said second portion of said upper surface, whereby a plurality of erect containers may be stacked one on top of another and the complementary portion of a leg of a first container resting on the per surface of the side walls of the adjacent container below said first container.
Preferably the second portion extends upwardly at about 12xc2x0 to the horizontal.
The invention is also applicable to cardboard walled containers where a concertina folded corrugated cardboard wall is held inside of the perimeter edge wall with stack locators with said 12 degrees.
In the known art the upper surface of the side walls is usually horizontal. Likewise the lower surface of the legs or feet in the known at is usually flat. We acknowledge the known art may have castellated surfaces or ledges to make location more positive. In the above mentioned format the 12 degree downward slope towards the exterior of the walls in combination with the downward slope of the outer edges of the legs of a similar 12 degree slope is claimed as an invention.
The phenomena of pressure induced sliding of bins moulded from polyethylene can cause the walls to bow and upper box to slide into the lower. The geometry of the underside of the foot and the corresponding sloped edge reverses this, and in fact induces the walls inwards, making the stack inherently more stable as the walls are pushed against the locating feet.